Lasix (Furosemide). Dosage, Side Effects, Interactions
Lasix (Furosemide) is a diuretic and is used to treat cardiovascular diseases such as hypertension and edema due to heart failure and hyperkalemia.
The active ingredient furosemide is used in a variety of diseases. The most common areas of application are high blood pressure (hypertension) and edema resulting from heart failure , liver and kidney diseases or burns. For hyperkalemia, furosemide is used to flush out excess potassium. The active substance is used improperly to make it more difficult to detect doping substances.
How Lasix works
Furosemide is a potent, short-acting, and rapidly acting loop diuretic . It blocks a transport mechanism for sodium, potassium and chloride ions in the kidney. This leads to increased excretion of these substances, so-called electrolytes, and the associated osmotically bound water. Furosemide thus promotes the flushing out of water accumulations in the tissue, so-called edema, which relieves the heart.
The excretion of calcium and magnesium ions is also increased. In addition, there can be reduced uric acid excretion and disturbances in the acid-base balance in the direction of metabolic alkalosis.
Furosemide also leads to a dose-dependent stimulation of the renin-angiotensin-aldosterone system. In heart failure , it acutely reduces the preload of the heart by expanding the venous capacity vessels. This early vascular effect is probably mediated by prostaglandins. It requires adequate kidney function with activation of the renin-angiotensin-aldosterone system and intact prostaglandin synthesis.
Furosemide has a blood pressure-lowering effect as a result of increased sodium chloride excretion and a reduced response of the smooth vascular muscles to vasoconstrictive stimuli and as a result of a decrease in blood volume.
After oral administration, 60-70% of furosemide is absorbed from the gastrointestinal tract. In patients with chronic heart failure or nephrotic syndrome, absorption may be reduced to less than 30%. The effect occurs after about 30 minutes. Maximum plasma levels are measured after about 1 hour, and after about 3.5 hours for the sustained-release form.
Furosemide is approximately 95% bound to plasma proteins. The relative volume of distribution is 0.2 l/kg body weight (in neonates 0.8 l/kg body weight).
Only about 10% of furosemide is metabolized in the liver and excreted mostly unchanged. Two-thirds of elimination is renal, one-third via bile and faeces.
With normal renal function, the elimination half-life is approximately 1 hour. In end-stage renal disease, it can be extended to up to 24 hours.
Dosage of Lasix (Furosemide)
Edema due to diseases of the heart, liver or kidneys:
As a rule, adults take 40 mg furosemide as a tablet or 60 mg as a prolonged-release capsule as an initial dose. If there is no satisfactory diuresis, the single dose can be increased to 80 mg furosemide tablets after 6 hours. If the diuresis is still insufficient, another 160 mg furosemide tablet can be administered after a further 6 hours. In exceptional cases, starting doses of more than 200 mg tablets or 120 mg prolonged-release capsules can be used with careful clinical monitoring.
The daily maintenance dose is usually 40-80 mg furosemide or 60 mg furosemide prolonged-release capsules daily or every 2nd or 3rd day.
The initial dose of the injection solution is 20-40 mg furosemide iv. In the case of edema that is difficult to mobilize, this dose can be repeated until diuresis occurs.
The weight loss caused by the increased diuresis should not exceed 1 kg/day.
In the case of nephrotic syndrome, the dose must be carefully dosed because of the risk of increased side effects.
As a rule, 40 mg tablets or 60 mg furosemide prolonged-release capsules should be taken daily alone or in combination with other medicines. In more severe cases, 120 mg of furosemide prolonged-release capsules daily can be administered initially.
Edema due to burns:
The daily and/or single dose can be between 40 mg and 100 mg furosemide (orally or iv), in exceptional cases with impaired kidney function up to 240 mg orally or 250 mg intravenously.
An intravascular volume deficiency must be compensated for before use.
Oliguria in advanced and terminal renal insufficiency (predialytic stage and stage requiring dialysis):
To increase diuresis, daily doses of up to 1000 mg furosemide can be given orally while monitoring the state of hydration and the serum electrolytes. The diuresis-increasing effect should be checked by occasional withdrawal attempts. Patients with chronic renal failure can only switch to furosemide 250 mg and gradually up to 1000 mg if the response to an oral dose of 120 mg furosemide per day is insufficient.
Acute renal failure:
In patients with shock, the hypovolaemia and hypotension should be eliminated before starting treatment, and the clearly pronounced disturbance of the serum electrolytes and the acid-base balance should be corrected. If furosemide 40 mg intravenously does not lead to increased fluid excretion, treatment with furosemide 250 mg solution for infusion can be started. A perfusor can be used to apply 50–100 mg of furosemide per hour. The daily dose depends on sufficient diuresis and should not be higher than 1500 mg furosemide per day.
Chronic renal failure in the predialytic stage with fluid retention and hypertension, nephrotic syndrome:
Since the natriuretic response depends on many factors, e.g. B. degree of renal insufficiency, sodium balance, etc., the correct dose should best be determined by escalating the dose. Due to the rapid onset of action, the dose can be increased every half hour to every hour, with the recommended starting dose being 0.1 mg per minute as an infusion. The dose should be chosen so that the patient loses around 1 kg of weight per day.
In the case of nephrotic syndrome, the dose must be carefully dosed due to the risk of increased side effects.
Pulmonary edema (e.g. in acute heart failure):
The initial dose is 20-40 mg furosemide iv in combination with other therapeutic measures. If there is no increase in diuresis, it can be repeated after 30-60 minutes, if necessary with a double dose.
As a supportive measure for cerebral edema:
The daily and/or single dose can be between 40-100 mg furosemide intravenously, in exceptional cases with impaired renal function up to 250 mg furosemide.
Oliguria due to gestosis:
An intravascular volume deficiency must be compensated for before the injection solution is used. The dosage can be between 10-100 mg furosemide daily. Edema and/or hypertension with gestosis are not an indication, the strictest indication applies!
20-40 mg furosemide iv in addition to other therapeutic measures is possible.
Use in children:
Children generally receive 1 (to 2) mg furosemide per kg body weight per day, up to a maximum of 40 mg furosemide per day. Furosemide oral oral solution is commercially available. Babies and children under the age of 15 should only be given parenteral furosemide in exceptional cases in the event of a threatening condition. The average daily dose is 0.5 mg furosemide/kg body weight, in exceptional cases up to 1 mg furosemide/kg body weight can be injected intravenously.
Type and duration of use
The duration of use depends on the type and severity of the disease. The dosage should be determined individually. The lowest dose that achieves the desired effect should always be used.
The tablets/sustained-release capsules should be taken on an empty stomach and not chewed with sufficient liquid, and the oral solution should be taken on an empty stomach.
Furosemide is given intravenously only when oral administration is impossible or ineffective, or when a rapid effect is required. Parenteral use of furosemide should be switched to oral administration as soon as treatment permits. Furosemide injection solution is usually administered intravenously. Furosemide injection solution can only be administered intramuscularly in exceptional cases in which neither oral nor intravenous administration is possible, but not in acute situations (eg not in pulmonary edema) and not in higher doses. For intravenous use, the solution for injection should be injected slowly. The injection rate of 4 mg furosemide per minute must not be exceeded while in patients with advanced renal failure 2, 5 mg furosemide per minute should not be exceeded. Doses above 250 mg furosemide should be administered via a perfusor. If necessary, the injection or infusion solution can be diluted with isotonic sodium chloride solution, but must not be injected together with other medicines. As precipitation of the active substance can occur, care must be taken to ensure that the pH of the ready-to-use injection or infusion solution is in the slightly alkaline to neutral range (pH not below 7). Acidic solutions must not be used. As precipitation of the active substance can occur, care must be taken to ensure that the pH of the ready-to-use injection or infusion solution is in the slightly alkaline to neutral range (pH not below 7). Acidic solutions must not be used. As precipitation of the active substance can occur, care must be taken to ensure that the pH of the ready-to-use injection or infusion solution is in the slightly alkaline to neutral range (pH not below 7). Acidic solutions must not be used.
Side effects of Lasix (Furosemide)
Furosemide side effects are listed below according to how common they are:
- Electrolyte disorders, dehydration, hypovolemia
- Blood triglycerides increased
- Hypotension including orthostatic syndrome (particularly with intravenous infusion)
- Circulatory disorders and collapse (with excessive diuresis, particularly in the elderly and children), including headache, dizziness, visual disturbances, dry mouth and thirst
- Increase in serum creatinine.
- Hemoconcentration (with excessive diuresis)
- Hyponatraemia and hypochloremia (apathy, leg cramps, loss of appetite, weakness, drowsiness, vomiting and confusion)
- Hypokalemia (muscle weakness, paraesthesia, paresis; vomiting, constipation, meteorism; polyuria, polydipsia and cardiac impulse formation and conduction disorders)
- Increased blood cholesterol, increased blood uric acid and gout attacks
- Hepatic encephalopathy in patients with hepatic insufficiency
- increased urine volume.
- Allergic skin and mucous membrane reactions
- Impaired glucose tolerance and hyperglycemia
- Mostly reversible hearing impairment, especially in patients with renal insufficiency or hypoproteinemia and/or with too rapid intravenous injection; deafness (possibly irreversible)
- Pruritus, urticaria , rashes, dermatitis bullous, erythema multiforme, pemphigoid, exfoliative dermatitis, purpura, photosensitivity.
- Eosinophilia, leukopenia
- Severe anaphylactic and anaphylactoid reactions (first signs of an anaphylactic shock include skin reactions such as flushing or urticaria , restlessness, headache, sweating, nausea, cyanosis)
- tinnitus aurium
- vomiting, diarrhea
- tubulointerstitial nephritis
- Hemolytic anemia, aplastic anemia, agranulocytosis
- Acute pancreatitis
- Intrahepatic cholestasis, increase in hepatic transaminases.
The following drugs can reduce the effect of furosemide:
- Nonsteroidal anti-inflammatory drugs (e.g. acetylsalicylic acid , indomethacin ). In the case of hypovolaemia or dehydration, the concomitant administration of non-steroidal anti-inflammatory drugs can trigger acute renal failure.
- Drugs that are significantly tubularly secreted in the kidneys like furosemide (e.g. probenecid , methotrexate )
- sucralfate (reduces the absorption of furosemide from the gut). Both drugs should not be taken together, but at least 2 hours apart.
In addition, there are numerous other interactions:
Simultaneous use with glucocorticoids , carbenoxolone or laxatives can lead to increased potassium losses. This creates a risk of hypokalemia. Large amounts of licorice act like carbenoxolone in this regard.
The sensitivity of the myocardium to cardiac glycosides may be increased when used concomitantly with furosemide.
There is an increased risk of ventricular arrhythmias (including torsades de pointes) with concomitant use of drugs that can cause prolonged QT interval syndrome (e.g. terfenadine , some class I and III antiarrhythmics ) and in the presence of electrolyte disturbances.
Toxicity of high-dose salicylates may be increased when used concomitantly with furosemide.
Furosemide can increase the harmful effects of nephrotoxic drugs (e.g. antibiotics such as aminoglycosides, cephalosporins , polymyxins).
Simultaneous use with ototoxic drugs (e.g. aminoglycoside antibiotics ) should be avoided, since their ototoxicity can be increased. Occurring hearing disorders can be irreversible.
Hearing damage is possible with the simultaneous use of furosemide with cisplatin. There may also be an increase in the nephrotoxicity of cisplatin .
The simultaneous administration of furosemide and lithium leads to an increase in the cardiotoxic and neurotoxic effects of lithium due to reduced lithium excretion. Lithium plasma levels should be carefully monitored.
With simultaneous use with other antihypertensives , diuretics or drugs with antihypertensive potential, an increased drop in blood pressure is to be expected. Massive drops in blood pressure have been observed particularly with ACE inhibitors or angiotensin II receptor antagonists. Before starting or increasing the dose of an ACE inhibitor or angiotensin II receptor antagonist, furosemide treatment should be temporarily stopped or the dose reduced for at least 3 days.
Furosemide may decrease the renal elimination of probenecid, methotrexate and other medicinal products which, like furosemide, are extensively renally tubularly secreted. With high-dose treatment (particularly with both furosemide and the other drug), this can lead to increased serum levels and a greater risk of side effects from furosemide or the concomitant medication.
Furosemide may potentiate the effects of theophylline and curare-like muscle relaxants.
The effect of antidiabetics or blood pressure-increasing sympathomimetics (e.g. epinephrine , norepinephrine ) can be weakened if furosemide is used at the same time.
A higher incidence of mortality has been observed in elderly patients with dementia when treated concomitantly with risperidone . Caution should therefore be exercised when combining it with risperidone, and the risks and benefits should be weighed before deciding on therapy.
Hypersensitivity to furosemide, sulfonamides (possible cross-allergy with furosemide) or any other component of the corresponding medicinal preparation.
In addition, the active ingredient must not be used in:
- Renal failure with anuria unresponsive to furosemide therapy
- Coma and praecoma hepaticum associated with hepatic encephalopathy
- severe hypokalemia
- severe hyponatraemia
- hypovolemia or dehydration
Furosemide crosses the placenta and reaches 100% of the maternal serum concentration in the umbilical cord blood. Malformations that could be associated with furosemide exposure have not been reported in humans to date. However, there is insufficient experience to make a final assessment of a possible harmful effect on the embryo/foetus.
During pregnancy, it should only be used for a short time and under particularly strict indications. Diuretics are not suitable for the routine treatment of hypertension and edema in pregnancy because they impair placental perfusion and thus intrauterine growth. If furosemide has to be used in cardiac or renal insufficiency in a pregnant woman, electrolytes and hematocrit as well as fetal growth should be closely monitored. For furosemide, a displacement of bilirubin from the albumin binding and thus an increased risk of kernicterus in hyperbilirubinemia is discussed.
Furosemide is excreted in breast milk and inhibits lactation. Women should therefore not be treated with furosemide while breastfeeding. If necessary, weaning must be done.
The ability to actively participate in road traffic, to operate machines or to work without a secure footing can be impaired by individually occurring different reactions. This applies to a greater extent at the start of treatment, when the dose is increased and when the drug is changed, as well as in combination with alcohol.
Further details on this active ingredient can be found in the relevant product information.
Looking where to buy Lasix (Furosemide) online without a prescription? Order now on our website! We deliver orders all over United States. The best drug prices are only available in our authorized online pharmacy